import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 苏西西
 * Date: 2024-01-03
 * Time: 15:29
 */
//针对用户表提供的基本操作
//由于我们没有注册功能，就不用写add
//也没有删除账号功能，就不需要delete
public class UserDao {
    //1.根据 userId来查用户信息
    public User selectById(int userId){
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try{
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造SQL
            String sql = "select * from user where userId = ?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,userId);
            //3.执行sql
            resultSet = statement.executeQuery();
            //4.遍结果集合
            if(resultSet.next()){
                User user = new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return null;
    }

    //2.根据username 来查用户信息（登录的时候）
    public User selectByUsername(String username){
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try{
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造SQL
            String sql = "select * from user where username = ?";
            statement = connection.prepareStatement(sql);
            statement.setString(1,username);
            //3.执行sql
            resultSet = statement.executeQuery();
            //4.遍结果集合
            if(resultSet.next()){
                User user = new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return null;

    }

}
